IN Brief:
- Haiyang Unit 5 began safety-related nuclear island concrete work on 31 October following construction licensing in China.
- Contractor CNNC 24 planned an approximately 6,626m³ first pour lasting nearly 62 hours.
- Unit 6 has its own regulatory hold point before its first nuclear island concrete, despite receiving a construction licence.
State Power Investment Corporation has begun main construction of Haiyang Unit 5 in China’s Shandong province after the first safety-related concrete was poured for its nuclear island on 31 October. Unit 5 is the first reactor in the plant’s third development phase, which is planned to add two CAP1000 pressurised water reactors. Construction began after China’s National Nuclear Safety Administration granted separate licences for Units 5 and 6, permitting the approved scope of safety-related civil engineering work.
China Nuclear Industry 24 Construction Co Ltd (CNNC 24), the civil construction contractor for the two Phase III nuclear islands, is carrying out the foundation works. The first concrete operation for Unit 5 involves approximately 6,626 cubic metres, with a planned duration approaching 62 hours. A placement on that scale requires sequencing of deliveries, continuous coordination between mixing, transport, and placement equipment, and quality checks throughout the operation. The timing describes the planned pour rather than a subsequently confirmed completed duration.
The start of safety-related foundation concrete moves Unit 5 beyond preparation and excavation into the principal nuclear construction programme. Structural concrete in a nuclear island supports the reactor building and associated safety-related equipment, so the design, reinforcing arrangements, constituent materials, and inspection records are subject to detailed control. Concrete temperature and curing behaviour also have to be managed to reduce the risk of thermal cracking during a large placement. CNNC 24 had reviewed construction arrangements and preparatory work before starting the pour.
The National Nuclear Safety Administration dated both construction licences 29 October, and the Ministry of Ecology and Environment issued the notice on 30 October. Inspectors had confirmed that Unit 5 was ready for its first nuclear island foundation concrete. Unit 6, although also licensed, has a separate regulatory hold point before the corresponding first pour. The responsible North China nuclear and radiation safety supervision station must release that point before the work can start on the second new reactor.
Both licences require construction quality assurance, progress reporting, and controlled management of changes to approved safety documentation. Welding of the main coolant pipelines is identified as a further hold point for each unit. These conditions tie regulatory supervision to particular construction activities, including work that will take place after the initial foundation is complete. The plant operator must maintain the required records and obtain approval where changes affect the commitments contained in the design and safety assessment documents.
Haiyang Unit 5 uses the CAP1000, a Chinese-developed pressurised water reactor design derived from the Westinghouse AP1000. World Nuclear Association data gives a net electrical rating of 1,161MW and a gross rating of 1,253MW. Primary circuit water carries heat from the reactor core at pressure, transferring that energy through steam generators to a separate secondary circuit. The steam drives turbine-generator equipment, while the design also incorporates passive safety provisions intended to perform specified functions during accident conditions.
The site’s first development phase contains two AP1000 units, which entered commercial operation in October 2018 and January 2019. Units 3 and 4, both CAP1000 reactors, are under construction as Phase II; Unit 3 entered construction in July 2022, followed by Unit 4 in April 2023. Phase III therefore adds another major civil engineering programme alongside an operating two-unit nuclear station and two further reactors at different stages of delivery, increasing the coordination required for access, workforce deployment, and common infrastructure.
China’s State Council approved the Phase III expansion in April 2025. When Units 5 and 6 are completed and commissioned, Haiyang is planned to comprise six large reactors across three phases. The new units will require progressive equipment installation, reactor system testing, turbine-generator checks, grid connection, and operating approvals. Each activity has its own engineering and regulatory sequence; the first concrete pour establishes a construction start and precedes the work needed to produce electricity from the two additional reactors.
Haiyang’s existing reactors also supply heat to centralised district heating systems in Shandong, including networks serving Haiyang and Rushan. Using heat from a nuclear generating station for district heating connects power production with a separate network of heat exchangers, pumps, and distribution infrastructure. The site has longer-term plans to extend both electrical generation and heating services as additional units enter operation, although projected future energy production and heating coverage depend on completion of the remaining reactor programme.
Following the initial Unit 5 foundation work, CNNC 24 will continue nuclear island construction under the quality and safety controls attached to its contract and the operator’s licence. Major structural works must progress before installation and testing of the reactor’s systems can follow. Unit 6 may undertake activities within its licensed scope, but its first safety-related concrete pour needs the separate regulatory release. Those distinct construction stages will determine the sequence of further milestones at the six-unit Haiyang site.
